Recovery of Phenolic Compounds from Switchgrass Extract

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Recovery of Phenolic Compounds from Switchgrass Extract. Michelle L Lehmann, Robert M. Counce, Robert W Counce, Jack S. Watson, Nicole Labbe, and Jingming Tao ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.7b02639 • Publication Date (Web): 15 Nov 2017 Downloaded from http://pubs.acs.org on November 19, 2017

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ACS Sustainable Chemistry & Engineering

Recovery of Phenolic Compounds from Switchgrass Extract.

Michelle L. Lehmann1, Robert M. Counce1*, Robert W. Counce1, Jack S. Watson1, Nikki Labbé2, Jingming Tao2 1

Department of Chemical and Biomolecular Engineering, 419 Dougherty Engineering Building, 1512 Middle

Drive, University of Tennessee, Knoxville, TN, 37996-2200 2

Center for Renewable Carbon, 2506 Jacob Drive, University of Tennessee, Knoxville, TN 37996-4542 * Robert Counce: [email protected]; Tel.: 865 974-5318

Abstract: The sorption/desorption of gallic acid, a simple phenolic compound, was studied experimentally in a batch system. The motivation for this project was to provide insight to the recovery of phenolic compounds from switchgrass. Recovery of phenolic compounds could enhance the sustainability and economics of biorefining facilities. The sorption/desorption of gallic acid was shown to be qualitatively similar to that of phenolics extracted from switchgrass; so more extensive studies were made using gallic acid as a surrogate for the complex mixtures of phenolic compounds leached from switchgrass.

The kinetics indicate that an

approximation of equilibrium was reached within 48 hours. Activated carbon was demonstrated to sorb gallic acid and phenolics from water and aqueous switchgrass leachate. The loading capacity of activated carbon for the gallic acid-water-activated carbon system increased with temperature for 20°C to 60°C. Ethanol was shown to be a preferable elution agent for desorbing gallic acid from activated carbon. Experimental observations and data from this study provide suitable design information that can be used for preliminary evaluation of conceptual designs of an activated-carbon based packed-bed process for recovery of phenolic compounds from aqueous switchgrass leachate. Key Words: Switchgrass, adsorption, phenolics, gallic acid, activated carbon. Introduction

The purpose of this study was to provide conceptual design information for the recovery of phenolic compounds from switchgrass extracts such as that proposed by Counce et al. [1]. Such extracts may have significant value and improve the sustainability of the production of ethanol fuels from renewable sources such as switchgrass. The phenolic compounds show promise for use as value-added antimicrobial products [2-5]. Switchgrass is used as a feedstock for bioprocessing of liquid fuels such as ethanol and advanced biofuels. Martin et al. [6] suggested an extraction step for phenolic compound recovery could be incorporated in a biorefinery prior to biochemical conversion to liquid fuels. A process for separating biomass into cellulose, hemicellulose, lignin as well phenolic fractions was developed by da Costa Lopes et al. [7] using ionic liquids that included a phenolic recovery step. The current study may be characterized as development of enabling technology for the biofuels industry using readily available materials, water and ethanol to enhance the sustainability of biorefining facilities. Phenolic compounds are known to have antioxidant and anti-inflammatory properties. They can be used in the pharmaceutical, cosmetic and nutritional industries and have recently been shown to reduce inflammation in fat tissue [8]. Bischoff [9] indicated that the biological effects of quercetin (a C-15 phenolic compound) included antihypertensive effects and improvement in endothelial function. Comparison of total phenolics and

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oxygen radical absorbance capability of switchgrass compared moderately well with those of other potential energy crops [10]. Removal of phenolics prior to fermentation has also been shown to increase the available sugar content of the biomass [11]. This is another way removal of phenolics compounds can enhance the sustainability of biorefining facilities. After leaching of phenolic compounds from biomass such as switchgrass, sorption is a simple process for the separation of phenolics from the complex aqueous solution; it involves relatively low cost and can be easily scaled to industrial sized operations. The sorption of phenolic compounds has been reviewed by Soto et al. [12]. Activated carbon (AC) has been shown to have a high adsorption capacity for phenolic compounds [13-15], although the ability for these compounds to be eluted from AC depends on the phenolic studied [16-21]. AC is made from a renewable source; it can be produced from any plant material with high carbon content. AC can also be regenerated several times, increasing its life expectancy. The value added product of interest for this study is the use of switchgrass extracts as a whole for applications as a bio-pesticide [3]. Switchgrass extracts as a group has been shown to have synergistic activities against various plant pathogens, thus determining the single phenolics in the extract was not necessary for this study. This study utilizes a surrogate phenolic compound to provide insight into the recovery of phenolics from aqueous extracts of switchgrass with AC as the adsorption media. Switchgrass extracts have a diverse array of phenolic compounds and the use of gallic acid is a standard method to evaluate the total phenolic content. Thus the surrogate phenolic selected was gallic acid, which is a common and significant phenolic compound that is found in a variety of plant materials. Use of a surrogate compound enables a more comprehensive sorption/desorption study to be performed over a wide range of conditions that would not be practical with the complex extract mixtures. It also eliminates the minor variability associated with different batches of switchgrass. A large number of phenolic compounds are extracted from switchgrass with high temperature (100°C) water, and all of these compounds are believed to have potential value for several applications. Although characterization of the mixture of phenolic compounds leached from switchgrass is difficult and may depend upon leaching conditions, initial studies have focused on the mixture itself, not the individual phenolic compounds. Some applications are expected to utilize the mixture rather than individual compounds. For these initial studies, the quantitative measure of the phenolic compound mixture was based upon measurement from Folin-Cioncalteau’s analysis for total phenolics and the results were expressed in terms of the gallic acid equivalent. Recovery of the extracted phenolic compounds by adsorption and elution was studied using both gallic acid and actual extract from switchgrass. The total gallic acid equivalent of the extract is a characterization that allows an approximate measurement of the antimicrobial efficacy of these extracts in the extract material. Gallic acid (GA) is a single phenolic compound and was used to provide insight into the recovery of phenolics from switchgrass extracts.

Materials and Methods Materials

All reagents used were analytical grade. The GA was 98% pure and obtained from Acros. The Activated Carbon was Fisherbrand, Catalog NO. 05-685AH, 6–14 mesh purchased from Fisher Scientific . Azeotropic


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ethanol (190 proof) was purchased from Decon labs. Sodium Carbonate powder and Folin-Ciocalteau’s phenol reagent were used to determine gallic acid (GA) and gallic acid equivalent (GAE) concentrations in solution. The Folin-Ciocalteau method is a simple, convenient and fast method to quantify the total phenolic compounds found in plant extractives. This method quantifies all soluble phenolic compounds present in solution when used with a standard. Gallic acid was used as the standard for all experiments. Absorbance readings were taken in triplicate at 765 nm using a Bio 3S UV-Vis Spectrophotometer. Extract Preparation Sorption/desorption tests of phenolic compounds from switchgrass extract were conducted using an aqueous extract of switchgrass grown within a 30 mile radius of Vonore, Tennessee. The switchgrass was harvested after senescence, air dried and chopped into 1-2 inch length. The extraction method was slightly modified from NREL protocol (NREL/TP-510-42619), using deionized (DI) water under 10,300 kPa pressure at 100 °C. The terms extract and extraction as used here is the same as the terms as leach and leaching. Experimental Procedure Adsorption rate experiments were performed with a 2.5 g/L aqueous solution of GA and the concentration in solution was monitored at regular time intervals until the adsorption rate approached zero. Adsorption equilibrium isotherms for GA from both aqueous and ethanol solutions were obtained using GA concentrations of 0.15 g/L to 5 g/L. These GA concentrations are similar to the GAE of the extract used in the tests. Batch sorption and desorption equilibrium studies for both GA and extract were performed. Sorption from aqueous solution and elution to ethanol were studied using GA concentrations of 0.5 g/L – 3 g/L. Adsorption studies with extract were performed using the extract as it was received. At the completion of the adsorption step, the AC was separated from the aqueous solution using Whatman No. 5 filter paper and rinsed 3 times with fresh DI water. Experiments were performed at 25°C. All experiments used 1-3 g of dry AC and a 100 mL volume of solution. The samples were agitated at 80 rpm in a thermostatic shaker and contacted for 48 hours. The total phenolic content of switchgrass extracts was estimated as gallic acid equivalents (GAE) using a microscale Folin-Ciocalteau colorimetry method [22]. The loading q (mmol/g) of the AC at the conclusion of each batch sorption tests was determined by =

( )

(1)

Co and Cf are the initial and final concentrations (mmol/L) of GA in the liquid phase; V is the volume of solution; (L) and W is mass of AC (g). The AC loading (q’, mmol/g) at the conclusion of each batch desorption test was determined by ′ =

( )

(2)

Cd is the concentration (mmol/L) of GA in the desorption solution; CL (equal to C0 – Cf) is the concentration (mmol/L) of GA loaded onto the AC during adsorption and V´ is the volume of solution. The desorption efficiency of the AC was determined by

(%) = 100(1 − )


(3)


Results and Discussion Gallic Acid Kinetic Studies. The adsorption kinetics of GA from water were studied at two temperatures, 20oC and 40oC and the data is presented in Figure 1. The adsorption profile indicates a 48 hour contact time is required to reach approximate equilibrium for both temperature conditions. This was the time used in all subsequent equilibrium measurements. This time also gave a first estimate of the size of adsorption bed needed for packed bed adsorption equipment, but adsorption rates are likely to be somewhat higher in packed beds where fresh solutions of phenolic compounds would be supplied continuously to the adsorption front.

q (mmol/g)

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Figure 1. Kinetic plot for Sorption of Gallic Acid from Water onto Activated Carbon.

Adsorption Isotherms. The equilibrium adsorption isotherms for GA from water are presented in Figure 2. The results for low temperatures (20°C) behaved approximately like a Langmuir isotherm with an approach to a maximum value at high concentrations. At higher temperatures, the adsorption equilibrium loading actually increases. This finding is unusual for adsorption processes, but it agrees with earlier phenolic adsorption works of Garcia-Araya et al. [23], Michailof et al. [24] and Gogoi et al. [14]. Such an increase in adsorption rate with temperature, can indicate that the process is endothermic. However, there is an increase in loading capacity as well as the loading rate, and that could indicate a chemical change in the carbon surface or the phenolic compounds at high temperatures, but one should note that the compounds were originally leached from switchgrass at an even higher temperature. In this study for preliminary process evaluations, adsorption temperatures were limited to 20°C where there was no indication of chemical alternation of the phenolic compounds.


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q (mmol/g)

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Figure 2. Adsorption Isotherms of Gallic acid from Water onto Activated Carbon at 20°C, 40°C and 60°C. The maximal experimental loading capacity can be approximated by the Langmuir equation: =

(6)

q is the loading of GA per gram of AC; Cf the concentration of GA remaining in solution; qm is the maximum single layer sorption capacity and KL is related to sorption enthalpy. At 20°C the maximum loading is approximately 1.59 mmol/g. For 40°C and 60°C the maximum loading is approximately 2.02 mmol/g and 2.40 mmol/g respectively. The increase in GA sorption with temperature makes the use of high temperature water to elute (desorb) GA unlikely, but does increase the loading capacity of AC. One would prefer to elute with a fluid that would produce lower GA loading, possibly ethanol or methanol. The isotherm in Figure 2 has a negative curvature over the entire concentration range. This indicates that the GA adsorption from water is favorable at all concentrations examined and should give sharp fronts during AC loading in packed beds.


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q (mmol/g)


Figure 3. Sorption of Gallic Acid from Azeotropic Ethanol onto Activated Carbon at 20°C and 40°C.

Since higher temperature water does not appear to be a suitable eluting agent, at least not over the temperatures studied (up to 60°C), ethanol was investigated as an alternative. Ethanol and the facilities for removing excess water from ethanol would be available at a switchgrass-based biorefinery.

The equilibrium

adsorption results for GA from azeotropic ethanol, shown in Figure 3, indicate there is little if any significant difference in the loading of GA at 20°C or 40°C, the values agree within 5%. Even higher temperatures probably would reduce the phenolic loading, but the adsorption data from water raises some questions about possible chemical changes in the phenolics at high temperatures. The approximate linear isotherm in Figure 3 has a slope of 0.058 L/g. GA sorption from ethanol isotherm appears to have little curvature over the concentration range tested. The most important point is that the AC loading from azeotropic ethanol are much lower than the equilibrium loading from water; this indicates that ethanol is likely to be a suitable eluting agent. The loading from ethanol is approximately 20% of that of GA loading from aqueous solution over the concentration range studied. The lower equilibrium GA adsorption from ethanol is most likely due to the high affinity of ethanol for AC [25]. Similar isotherm profiles have been seen with AC adsorption of phenol [26, 27], p-nitrophenol [28] and grape pomace liquors [18]. As seen in Figures 2 and 3, GA loading onto AC from azeotropic ethanol is significantly lower than from aqueous solution.

Adsorption/Desorption Tests. Although the difference in the adsorption isotherms for water and ethanol suggest that ethanol would be a suitable eluting agent, there was a need to confirm that azeotrope ethanol can elute GA and/or actual phenolics in the extract from activated carbon.

Adsorption/ desorption studies included

desorption of both GA and switch grass extracts (GAE) and confirm that absorption of GA and GAE from


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aqueous solution and desorption into ethanol is feasible. As seen in Table 3, loading of GAE from the aqueous extract is decreased to that of GA. A similar decrease in loading was also seen by Soetaredjo et al. [16] when a waste water sample was compared to pure catechin and epicatechin. In Figure 4, the desorb values of aqueous GA and GAE are shown. GA has a higher qꞌ than GAE of the extract, indicating that more GA remains on the carbon after desorption than the phenolics in the extract at similar concentrations. The experimental results indicate that desorption of GA and GAE from AC is feasible. The results may be used for conceptual design purposes. There is evidence that there can be differences in the behavior of some phenolics during adsorption and desorption on AC. Couteau and Mathely [13] achieved quantitative elution of adsorbed ferulic acid with ethanol, while Aehle et al. [17] and Sato et al. [18] achieved minimal desorption of crude spinach and grape pomace extracts respectively. Ionic liquid assisted sorption of phenolic compounds onto various polymeric resins was demonstrated by Costa Lopes et al., with the best performance obtained with Amberlite XAD-7 [7]. However, considering that GAE in switchgrass extract behaved similar to GA which can be sorbed from water and eluted efficiently with ethanol, there is indication that reasonable desorption efficiencies can be achieved for switchgrass phenolics with AC. Polymeric resins tend to desorb more effectively [17, 19] and could be a workable alternative to AC.

Table 3: Adsorption/ desorption values for GA and Extract at Different Initial Concentrations. All values obtained at 25°C. Co

Cf

q

Cd

q’

(mmol/L)

(mmol/L)

(mmol/g)

(mmol/L)

(mmol/g)

GA

2.94

0.171

0.276

0.355

0.241

12.8

GA

5.88

0.858

0.502

1.509

0.351

30.0

GA

8.82

1.423

0.739

2.930

0.447

39.6

GA

11.76

1.984

0.976

4.594

0.518

47.0

GA

17.65

5.104

1.250

6.039

0.648

48.2

0.90

0.669

0.023

0.099

0.018

21.7

3.64

0.654

0.100

1.181

0.060

39.7

Sample

Extract 1 Extract 2

D%

Of course, these adsorption/desorption curves were obtained from simple batch experiments that can not show complete or essentially complete polyphenolic recovery. The simple batch tests are quicker and require fewer chemical analyses than experiments with packed beds of AC. However, the results do suggest that essentially complete recovery would be possible when using a pack bed where continuous supply of fresh ethanol would force the desorption front down the bed leaving essentially no polyphenolics on the carbon.



Figure 4. Desorption Percent of Gallic Acid and Extract at Different Aqueous Concentrations. Although ethanol is an expensive solvent for elution compared to water, ethanol is produced in bio-energy facilities and can be used and reclaimed in such facilities. A study was performed to explore the possibilities of using more dilute ethanol solutions for desorption, as dilution will inevitably occur when desorbing wet AC with ethanol. The effect of water transfer from the carbon to the ethanol eluting agent is shown in Figure 5. It would require a large increase in the water content of the ethanol to affect the elution curves shown in Figure 4. As shown in Figure 5, there is less than a 5% difference in fractional desorption for ethanol concentrations of 45% -95%. At a 45% ethanol solution, there is likely enough ethanol in the eluting solution to displace GA from the sorption sites on the carbon surface. This indicates that a diluted ethanol solution can be effectively employed for desorption of GA. The very low fractional desorption ratio with pure water confirms that this is not effective in eluting GA from AC.

D (%)

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Figure 5. Desorption Efficiency of Gallic Acid with Varying Concentrations of Aqueous Ethanol Solutions.

Conclusion We have demonstrated that phenolics from switchgrass extract can be adsorbed onto AC and recovered into ethanol. Experimental observations and data from this study provide suitable design information for conceptual design of an activated-carbon based packed-bed process for recovery of phenolic compounds from aqueous leachate from switchgrass. The behavior of the complex mixture of switchgrass extract can be approximated by the reference compound of gallic acid. This study shows both a way to separate phenolic compounds from switchgrass extract as well as a way to study the sorption process of a complex phenolic extract without having to identify all of the numerous compounds involved. The sorption capacity of AC for GA in water was found to increase with increased temperature while no effect of temperature was observed with sorption from azeotropic ethanol. This work suggests effective elution with water at elevated temperatures is not likely to be practical and that finding led to the study of a GA-AC-ethanol-water equilibria system. The sorption of GA from ethanol at different temperatures has not been previously studied and is a new finding. GA sorption from ethanol isotherm has little curvature at the low concentrations of interest. The kinetic studies show a slow adsorption profile reaching steady state in 48 hours in batch experiments. This provides insight into the residence time required when sizing an industrial process and indicates that rather large carbon beds would be required. Though there is limited data for comparison; switchgrass extract phenolics were shown to adsorb somewhat less effectively than the gallic acid surrogate, but desorb more effectively. Desorption of GA and GAE into ethanol was demonstrated with experimental data with a desorption ratio up to 48%. These desorption results may be viewed as promising since they were carried out in batch tests; much higher desorption, perhaps approaching 100%, may be possible using packed beds. Reuse of AC for recovery of phenolic compounds is important sustainability factor and will need verification before AC reuse in future processes is assumed. The cost of enriching the ethanol elution agent and drying the phenolic products would have to be justified by the cost of the phenolic product.

Acknowledgments: Funding was provided by the Agriculture and Food Research Initiative Grant No. 013-67021-21158. Author Contributions: R.M.C. and N.L. conceived the project; M.L. and R.M.C designed the experiments; M.L. and R.W.C performed the experiments; M.L. analyzed the data; J.T. contributed materials; M.L., R.M.C and J.W. wrote the paper. Conflicts of Interest: The authors declare no conflict of interest.



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References 1.

2.

3. 4.

Counce, R.M., Labbé, N., Lehmann, M.L. Watson, J.S., Tao, J. Process for removal and recovery of phenolic compounds from switchgrass. 5th International Congress on Green Process Engineering (GPE 2016), Franco Berruti, Western University, Canada Cedric Briens, Western University, Canada Eds, ECI Symposium Series. 2016. http://dc.engconfintl.org/gpe2016/11 Bruce, A., H. B. Korotkin, B. H. Ownley, J. Tao, L. M. Kline, N. Labbe, K. D. Gwinn, D. H. D'Souza, and N. Moustaid-Moussa. Concentrated ethanol-derived switchgrass extractives inhibit plant and foodborne pathogens. Phytopathology 2015, 105(Suppl. 4):S4.20. Ownley B., J. Tao, N. Labbe, K. D. Gwinn. Switchgrass extractives inhibit plant pathogenic fungi. Phytopathology 2016, 106 (Suppl. 4):S4.50. Uppugundla, N.; Engelberth , A.; Ravindranath, S. V.; Clausen, E. C.; Lay, J. O.; Gidden, J.; Carrier, D. J. Switchgrass water extracts: Preparation and biological activity of rutin and quercitrin. J. Agric. Food Chem 2009, 57, 7763-7770. DOI: 10.1021/jf900998q

5.

Lindsey, K.; Johnson, A.; Kim, P.; Jackson, S.; Labbé, N. Monitoring switchgrass composition to optimize harvesting periods for bioenergy and value-added products. Biomass and Bioenergy 2013, 56, 29-37. https://doi.org/10.1016/j.biombioe.2013.04.023

6.

Martin, E. M.; Cousins, S. L.; Talley, S. R.; West, C. P.; Clausen, E. C.; Carrier, D. J. Effect of presoaking on extraction of hemicellulosic sugars and flavanoids from switchgrass (Panicum virgatum) leaves and stems. Transactions of the American Society of Agricultural and Biological Engineers 2011, 54(5), 1953 -1957. DOI: 10.13031/2013.39817

7.

Costa Lopes, A.M., Brenner, M., Falé, P., Roseiro, L., Bogel-Lukasik, R. Extraction and Purification of Phenolic Compounds from Lignocellulosic Biomass Assisted by Ionic Liquid, Polymeric Resins, and Supercritical CO2. ACS Sustainable Chem. Eng. 2016, 4, 3357−3367. DOI: 10.1021/acssuschemeng.6b00429

8.

Garrison, R.; Scoggin, S.; Siriwardhana, N.; Labbé, N.; Ownley, B.; Gwinn, K.; D'Souza, D.; Moustaid-Moussa, V. Anti-inflammatory effects of extracts from a bioenergy crop, switchgrass, in cultured adipocytes. The FASEB J 2015, 29(1), Supplement 721.48.

9.

Bischoff, S. Quercetin: Potentials in the prevention and therapy of disease. Current Opinion in Clinical Nutrition and Metabolic Care 2008, 11(6), 733-740. DOI: 10.1097/MCO.0b013e32831394b8

10. Lau, C.S.; Carrier, D.J.; Howard, L.R.; Jackson, O.L.Jr.; Archambault, J.A.; Clausen, E.C. Extraction

of Antioxidant Compounds from Energy Crops. Applied Biochemistry and Biotechnology 2004, 113-116, 569 – 583. https://doi.org/10.1385/ABAB:114:1-3:569 11. Kim, Y.; Ximenes, E.; Mosier, N.S.; Ladisch, M.R. Soluble inhibitors/ deactivators of cellulase

enzymes from lignocellulosic biomass. Enzyme Microb. Technol 2011, 48, 408–415. https://doi.org/10.1016/j.enzmictec.2011.01.007 12. Soto, M. L., Moure, A., Domínguez, H., Parajó, J. C. Recovery, concentration and purification of

phenolic compounds by adsorption: A review. Journal of Food Engineering 2011, 105, 1–27. https://doi.org/10.1016/j.jfoodeng.2011.02.010 13. Ahmaruzzaman, Md. Adsorption of phenolic compounds on low-cost adsorbents: A review. Adv.

Colloid Interface Sci 2008, 143(1-2), 48-67. https://doi.org/10.1016/j.cis.2008.07.002 14. Couteau, D.; Mathaly, P. Fixed –bed purification of ferulic acid from sugar beet pulp using activated

carbon: Optimization studies. Bioresource Technology 1998, 64(1), 17 – 25. https://doi.org/10.1016/S0960-8524(97)00152-1 15. Gogoi, P.; Dutta, N.; Rao, P. G. Adsorption of catechin from aqueous solutions on polymeric resins

and activated carbon. Indian Journal of Chemical Technology 2010, 17(5), 337-345.


Page 10 of 12

Page 11 of 12

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


16. Krammerer, D. R.; Saleh, Z. S.; Carle, R.; Stanley, R. A. Adsorptive recovery of phenolic compounds

from apple juice. Eur. Food res. Technol 2007, 224, 605 -613. https://doi.org/10.1007/s00217-006-0346-5 17. Soetaredjo, F.E.; Ismadji, S.; Santoso, S.P.; Ki, O.L.; Kurniawan, A.; Ju, Y. H. Recovery of catechin

and epicatechin from sago waste effluent: Study of kinetic and binary adsorption isotherm studies. Chemical Engineering Journal 2013, 231, 406-413. https://doi.org/10.1016/j.cej.2013.07.048 18. Achle, E.; Grandic, S. R.-L.; Ralainirina, R.; Baltora-Rosset, S.; Mesnard, F.; Prouillet, C.; Mariere,

J-C.; Fliniaux, M-A. Development and evaluation of an enriched natural antioxidant preparation obtained from aqueous spinach (Spinacia oleracea) extracts by an adsorption procedure. Food Chemistry 2004, 86, 579 -587. https://doi.org/10.1016/j.foodchem.2003.10.006 19. Sato, M. L.; Moure, A.; Dominguez, H.; Parajo, J. C. Charcoal adsorption of phenolic compounds

present in distilled grape pomace. Journal of Food Engineering 2008, 84, 156-163. 20. Otero, M.; Zabkova, M.; Grands, C.A.; El Rodrigues, A. Fixed bed adsorption of salicyclic acid onto

polymeric adsorbents and activated charcoal. Ind. Eng. Chem. Res 2005, 44, 927-936. DOI: 10.1021/ie049227j 21. Kim,Y.; Kreke, T.; Hendrickson, R.; Parenti, J.; Ladisch, M. R. Fractionation of cellulase and

fermentation inhibitors from steam pretreated mixed hardwood. Bioresourse Technology 2012, 135, 30-38. https://doi.org/10.1016/j.biortech.2012.10.130 22. Waterhouse, A.I. Determination of total phenolics. Current Protocols in Food Chemistry 2002,

II.1.1-II.1.8. DOI: 10.1002/0471142913.faa0101s06 23. Garcia-Araya, J. F.; Beltran, F.J.; Alverez, P.; Masa, F. J. Activated carbon adsorption of some

phenolic compounds present in agroindustrial wastewater. Adsorption 2003, 9, 107 – 115. 24. Michailof, C.; Stavropoulos, G.G.; Panayiotou, C. Enhanced adsorption of phenolic compounds,

commonly encountered in olive mill wastewaters, on olive husk derived activated carbons. Bioresource Technology 2008, 99(14), 6400-6408. https://doi.org/10.1016/j.biortech.2007.11.057 25. Nevskaiaa, D.M.; Santianesb, A.; Mun˜oza, V.; Guerrero-Ru´ıza, A. Interaction of aqueous solutions

of phenol with commercial activated carbons: an adsorption and kinetic study. Carbon 1999, 37, 1065–1074. https://doi.org/10.1016/S0008-6223(98)00301-7 26. Ravi, V.P.; Jasra, R.V.; Bhat, T. S. G. Adsorption of phenol, cresol isomers and benzyl alcohol from

aqueous solution on activated carbon at 278, 298 and 323 K. J. Chem. Technol. Biotechnology 1998, 71, 173-179. DOI: 10.1002/(SICI)1097-4660(199802)71:23.0.CO;2-N 27. Laatikainen, K.; Laatikainen, M.; Bryjak, M.; Sainio, T.; Siren, H. Adsorption of bisphenol from

water-ethanol mixtures on pulverized activated carbon. Separation Science and Technology 2014, 49, 763–772. http://dx.doi.org/10.1080/01496395.2013.860462 28. Haydar, S.; Ferro-Garcia, M.A.; Rivera-Utrilla, J.; Joly, J.P. Adsorption of p-nitrophenol on an

activated carbon with different oxidations. Carbon 2003, 41, 387–395. https://doi.org/10.1016/S0008-6223(02)00344-5



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An adsorption/ desorption process was studied using an activated carbon based system to separate phenolic compounds from switchgrass extract for use as a bio-pesticide.


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Recovery of Phenolic Compounds from Switchgrass Extract

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